Cutting tool for recessing and grooving

ABSTRACT

A cutting tool for radial and axial recessing and for lateral motion for so-called grooving of primarily metallic materials. The cutting tool has a clamping holder and a cutting element base, fastened to the clamping holder, on which a cutting element rests. The cutting element is pressed onto the cutting element base by a clamping finger of a clamping claw, and the cutting element being guided on the cutting element base with a prism.

This application is a §371 of International Application No.PCT/EP2011/063387 filed Aug. 3, 2011, and claims priority from GermanPatent Application No. 10 2010 038 878.5 filed Aug. 4, 2010, herebyincorporated by reference in its entirety.

The invention relates to a cutting tool for radial and axial recessingand for lateral motion for so-called grooving of primarily metallicmaterials, having a clamping holder and a cutting element base, fastenedto the clamping holder, on which a cutting element rests, the cuttingelement being pressed onto the cutting element base by a clamping fingerof a clamping claw, and the cutting element being guided on the cuttingelement base by means of a prism.

Such a cutting tool is disclosed in DE 10 2008 001135 A1.

The object of the invention is to improve a cutting tool together withits components according to the present invention in such a way thatlateral turning operations may also be carried out without the cuttingelement being able to come unscrewed from its seat. In addition, the aimis to prevent the clamping claw from turning away laterally.

This object is achieved according to the invention in that on its flatsurface facing the clamping finger the cutting element has twooppositely inclined flat rectangular roof slopes, in the manner of asaddle roof or gable roof of a house, which extend, starting at thesurface, into the cutting element, and on its bottom side facing thecutting element the clamping finger has two ramps which are adapted tothe slopes.

Since the cutting element on the one hand is guided on the cuttingelement base by means of a prism, and on the other hand has roof slopeson its surface in which corresponding ramps on the clamping fingerengage, the cutting element is guided on its top and bottom sides, andmay also carry out lateral turning operations without becoming unscrewedfrom its seat.

A ridge surface which forms part of the surface of the cutting elementis preferably situated between the two roof slopes. This ridge surfaceis necessary to prevent formation of a sharp edge which could press intothe clamping element or the clamping finger of the clamping claw. In theclamping element or in the clamping finger, a radius is present betweenthe two roof slopes.

In one embodiment of the invention, the ridge surface forms a rectanglehaving a shorter side and a longer side. The shorter side of therectangle is preferably equal to the width b of the ridge surface 9, andtherefore is equal to the distance between the roof slopes 7, and thelonger side of the rectangle is equal to the width B of the roof slopes.Optimal use is thus made of the available surface area.

In one preferred embodiment, the roof slopes extend at an angle of15°>α>5°, preferably a α=10°, with respect to the surface of the cuttingelement, the roof slopes extending, starting at the ridge surface, tothe edge of the cutting element. Only at these angles is the cuttingelement on the one hand weakened only to a slight extent, and on theother hand easily anchored in the cutting tool. At larger angles, i.e.,greater than 15°, the cutting element would be excessively weakened. Atangles less than 5°, the anchoring in the cutting tool is notsufficient.

The cuffing element base and the clamping claw are advantageously guidedon the clamping holder with a precise fit by means of a tongue andgroove connection, resulting in improved anchoring.

In one preferred embodiment, an inclined plane which is sloped to therear, i.e., away from the cutting element, and designed as a groove issituated on the clamping holder, and the clamping claw, having asimilarly inclined plane which is designed as a tongue, rests on thisgroove with a precise fit in the manner of a tongue and grooveconnection. As a result of this precise guiding, lateral turning away ofthe clamping element is avoided or is no longer possible.

To increase the clamping force of the clamping claw on the cuttingelement, bearing points designed as ribs are situated on the inclinedplane of the clamping claw on the end facing away from the ramps, andthe leadthrough for the clamping screw is situated on the opposite endof the inclined plane facing the ramps. A long lever arm thus acts whenthe clamping screw is screwed in, thereby increasing the clamping force.

A cutting element according to the invention is composed of a ceramicand/or CBN, having a flat top side and bottom side, and having sidesurfaces which connect the top and bottom sides. The cutting element ispreferably usable on the above-described cutting tool.

According to the invention, on its top side the cutting element has twooppositely inclined flat rectangular roof slopes, in the manner of asaddle roof or gable roof of a house, which extend, starting at thesurface, into the cutting element. These roof slopes allow twist-proofinsertion into a cutting tool.

A ridge surface which forms part of the surface of the cutting elementis preferably situated between the two roof slopes. This ridge surfaceis necessary to prevent formation of sharp edges.

In one preferred embodiment, the roof slopes extend at an angle of15°>α>5°, preferably α=10°, with respect to the surface of the cuttingelement, the roof slopes extending, starting at the ridge surface, tothe edge of the cutting element. Only at these angles is the cuttingelement on the one hand weakened only to a slight extent, and on theother hand easily anchored in the cutting tool. At larger angles, i.e.,greater than 15°, the cutting element would be excessively weakened. Atangles less than 5°, the anchoring in the cutting tool is notsufficient.

In one preferred embodiment the cutting element has protrudingengagement elements on its bottom side. The cutting element may thus beguided in a twist-free manner on its bottom side, and on its top sidevia the roof slopes. In one preferred design the engagement elements arespherical projections. The engagement elements are thereforeadvantageously part of a prism guide.

In one embodiment of the invention, the bearing surfaces of the top andbottom sides and/or the bevels of the cutting element have at leastpartial areas which are composed of the sinter skin which results duringsintering, and which have experienced no damage from material-removingtreatment. Refinishing after sintering is thus at least partiallyavoided.

In one preferred embodiment, the entire top and bottom sides arecomposed of the sinter skin which results during sintering. Since thesinter skin often has a greater hardness than the base material, thewear resistance of the cutting material is thus increased.

The greater the surface area of the cutting element that is composed ofthe sinter skin resulting during sintering, the greater the hardness.Therefore, preferably all bevels and/or sides are composed of the sinterskin which results during sintering.

Thus, in one embodiment of the invention, individual side surfaces orpreferably all side surfaces are composed of the sinter skin whichresults during sintering.

The top and/or bottom side and/or the side surfaces and/or the bevels ofthe cutting element may be provided with a one or multilayer coating toimprove the hardness.

A clamping claw according to the invention having a clamping finger, inparticular for the above-described cutting tool, is characterized inthat two oppositely inclined, flat rectangular ramps (8) are situated onthe clamping finger (4) as the inverse of a saddle roof or gable roof ofa house. The ramps are adapted to the roof slopes (7).

As mentioned above, the cutting element base and the clamping claw arepreferably guided on the clamping holder with a precise fit by means ofa tongue and groove connection. The cutting element base and theclamping claw are thus always in the required position.

In one embodiment of the invention, the clamping holder has a groove,and the cutting element base has a tongue on its side facing theclamping holder, the cutting element base being guided on the clampingholder with a precise fit by means of the tongue engaging in the groove.

Preferably, threaded holes are introduced into the groove and/or on thebearing surface of the cutting element base on the clamping holder, andthe cutting element base has boreholes matched to the number of threadedholes, and screws which pass through the cutting element base arescrewed into the threaded holes for fastening the cuffing element baseto the clamping holder. A simple, secure connection is established inthis way.

The cutting element base is preferably oriented at right angles to theclamping claw.

A fastening hole which extends at an angle y with respect to theinclined plane is introduced into the inclined plane, designed as agroove, on the clamping holder, and a clamping screw which passesthrough the clamping claw engages with the fastening hole for fasteningthe clamping claw to the clamping holder.

Further features of the invention are shown in the twelve figuresdescribed below:

FIG. 1: shows a cutting tool 1 according to the invention, having aclamping holder 2, cutting element base 3, clamping claw 5, and cuttingelement 6;

FIG. 2: shows the elements according to FIG. 1 in enlarged scale;

FIG. 3: shows the clamping holder 2 with the fastened cutting elementbase 3 and with the cutting element 6 placed thereon;

FIG. 4: shows only the clamping holder 2;

FIG. 5: shows only the clamping holder 2 with the fastened cuttingelement base 3;

FIG. 6: shows a clamping claw 5 according to the invention with theinserted clamping screw 17 in a [perspective] view;

FIG. 7: shows the clamping claw 5 without the inserted clamping screw;

FIG. 8: shows the clamping claw 5 from below;

FIG. 9: shows the clamping holder 2 according to FIG. 4 from the side;

FIG. 10: shows the clamping holder 2 from the top;

FIG. 11: shows the cutting element base 3 from the side (FIG. 11a ) andin cross section (FIG. 11b ); and

FIG. 12: shows the cutting element 6 according to the invention from thetop (FIG. 12a ) and in a [perspective] view (FIG. 12b ).

The clamping holder 2 described here is also referred to as a baseholder, the cutting element base 3 is also referred to as a partingblade, and the clamping claw 5 is also referred to as a parting insert.

The invention relates to a cutting tool 1 (see the figures) which in itsbasic design may be used alike for recessing, thread cutting, andgrooving. The cutting tool is always composed of a base support,referred to below as a clamping holder 2, an exchangeable cuttingelement base 3, and an exchangeable cutting element hold-down device,referred to below as a clamping claw 5. The cutting element base 3 andthe clamping claw 5 form the so-called clamping system, and are adaptedto the shape and function of the cutting element 6 used.

The clamping holder 2 (see FIGS. 1 through 5) has a guide groove 10 inthe axial direction (see FIG. 4), in the base of which a threaded hole11 is introduced. A tongue 24 protrudes into this guide groove 10 at theside of the cutting element base 3 facing the clamping holder 2. Thetongue 24 is inserted into the guide groove 10 with a precise fit, sothat the cutting element base 3 is precisely guided on the clampingholder 2.

For the positive-fit connection of the cutting element 6 on the cuttingelement base 3, the cutting element 6 is guided by a prism-shapedconnection, also referred to as a guide strip, between the bottom sideof the cutting element 6 and the top side of the cutting element base 3.Possible shape and position errors of the cooperating components arecompensated for by the same axial orientation of the components and themutually coordinated tolerances of the units, guides, and prisms in thetechnical sense of a clearance fit.

Furthermore, the cutting element 6 is also guided on its top side 15 a.For this purpose, the cutting element 6 has two oppositely inclined,flat rectangular roof slopes 7 in the manner of a saddle roof or gableroof of a house which extend, starting at the surface 12, into thecutting element 6. These roof slopes 7 allow twist-free insertion into acutting tool 1.

A ridge surface 9 which forms part of the surface 12 of the cuttingelement is situated between the two roof slopes 7. The four sides of theridge surface 9 form a rectangle. The shorter side is preferably equalto the distance b between the ridge surfaces 9, and the longer side ofthe rectangle is preferably equal to the width B of the roof slopes (seeFIG. 11a ).

In the embodiment shown here, the roof slopes 7 extend at an angle α=10°(see FIG. 12b ) with respect to the surface 12 of the cutting element 6,the roof slopes 7 extending, starting at the ridge surface 9, to theedge of the cutting element 6.

For anchoring the cutting element 6 to the cutting element base 3 with aprecise fit, the cutting element 6 has protruding engagement elements 23on its bottom side. The cutting element 6 is thus guided in a twist-freemanner on its bottom side 15 b, and on its top side 15 a via the roofslopes 7. The engagement elements 23 are preferably sphericalprojections. The engagement elements 23 are part of a prism guide.

Another feature is the special design and bearing of the clamping claw5, which is fastened to the top side of the clamping holder 2 by aclamping screw 17. The clamping claw 5 rests with its inclined plane 21on an inclined plane 16 on the clamping holder 2, and is guided with aprecise fit by the guide surface 18 (see FIGS. 3 through 8). Theclamping force of the clamping screw 17 presses the clamping claw 5 ontothe clamping holder 2 on the inclined plane 16 until the bearing points19 of the clamping claw arrive at the inclined plane 16. Furthertightening of the clamping screw 17 acts as a lever effect and clampsthe clamping finger 4 of the clamping claw 5 in the direction of thecutting element 6, thus exerting an additional clamping force on thecutting element 6. As a result of this clamping force the cuttingelement 6 is pressed into the prism, and the guide strip 14 is pressedonto the cutting element base 3.

To reinforce this lever effect, the bearing points 19 and theleadthrough 13 for the clamping screw 17 are situated at the maximumpossible distance from one another on the inclined plane 21.

The cutting element 6 is preferably made of a ceramic and/or PCBN or aCBN material.

The cutting element 6 may also be provided with a coating for increasingthe hardness.

FIG. 8 shows bearing points 19 designed as ribs. FIG. 8 also shows thatthe bearing points 19 are situated on the sloped inclined plane 16 ofthe clamping claw.

The invention claimed is:
 1. A cutting tool for radial and axialrecessing and for lateral motion for grooving primarily metallicmaterials, comprising: a clamping holder; a cutting element basefastened to the clamping holder, on which a cutting element rests,wherein the cutting element is pressed onto the cutting element base bya clamping finger of a clamping claw; wherein a bottom side of thecutting element is guided on a top side of the cutting element base witha prism-shaped connection, wherein on a flat surface of the cuttingelement facing the clamping finger there are two oppositely inclinedflat rectangular roof slopes which extend, starting from the flatsurface, downward into the cutting element, and on its bottom sidefacing the cutting element the clamping finger has two ramps which abutsaid flat rectangular roof slopes, wherein a ridge surface which formspart of the flat surface of the cutting element is situated between thetwo roof slopes, wherein the ridge surface has four sides and forms arectangle, and wherein a bottom surface of the clamping claw has asloped inclined plane with bearing points designed as ribs which restson a sloped inclined plane situated on a top surface of the clampingholder.
 2. A cutting tool according to claim 1, wherein the rectanglehas a shorter side and a longer side.
 3. A cutting tool according toclaim 2, wherein the shorter side of the rectangle is preferably equalto the width b of the ridge surface.
 4. A cutting tool according toclaim 1, wherein the roof slopes extend at an angle of 15°>α>5° withrespect to the surface of the cutting element, the roof slopesextending, starting at the ridge surface, to the edge of the cuttingelement.
 5. A cutting tool according to claim 1, wherein the cuttingelement base is guided on the clamping holder with a precise fit by atongue and groove connection.